What is the Militia?

One of the most common arguments gun-prohibitionists use is that
the term "militia" in the Second Amendment refers to
States' right to maintain an army -- that is, the National Guard.

We all know better, and here's proof. Following is a scan from
the 1771 edition of the Encyclopedia Britannica. You can see a
scan of the whole page, plus the cover page, in PDF format here.

The definition of militia reads:

MILITIA, in general, denotes the body of soldiers,
or those who make profession of arms......In a more restrained sense,
militia denotes the trained bands of a town or country, who
arm themselves, upon a short warning, for their own defence.
So that, in this sense, militia is opposed to regular or stated
troops. .....For the direction and command
of the militia, the king constitutes lords-lieutenants of each
country.